JPS63121069A - Image forming method - Google Patents

Abstract

PURPOSE:To obtain images of good quality which are free from photographic fog and have good gradation and have not negative characteristics by allowing a small quantity of magnetic particles to exist on a developing area. CONSTITUTION:A magnetic brush 51 is formed with toner particles holding fine silica powder on surfaces and magnetic particles so that 5-80mg/cm<2>, preferably, 10-70mg/cm<2> magnetic particles 27 exist on the developing area of a developer carrier. In the developing area, nonmagnetic toner particles 28 are moved back and forth between a latent image holding body and the surface of the developer carrier as well as the surface of the magnetic brush 51 formed on the surface of the developer carrier to develop a latent image. These nonmagnetic toner particles display only <=10emu/g magnetization in 5,000Oe external magnetic field and cannot practically act as a magnetic toner. Thus, excellent developed images are obtained with a very high development efficiency.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a developing method for forming a brush of a small amount of magnetic particles on a toner holding member using a dry developer for development.

[Conventional technology]

Conventionally, various methods have been proposed and put into practical use as dry development methods.

For example, in a developing method using a two-component developer, when an image area of a latent image is developed with the developer coated on the developing roller, the toner in the developer is absorbed by the developer coated on the developing roller. Only a few percent of this is used. This is extremely inefficient considering the structure of the developing device. This is because, in order to obtain a predetermined and sufficient development density, it is necessary to apply a large amount of developer to the developing roller in a constant amount and at a uniform toner density each time the developing roller rotates. For this reason, the developer configuration has been made larger and
It was getting complicated. For example, JP-A-55-32060, JP-A-55-133058, JP-A-56-7056.
According to the development method disclosed in Publication No. 0, etc.,
The development density can be increased, and the development efficiency can be increased. However, almost 100% in the image area
This type of development method has not been able to achieve a development efficiency close to that of the previous method, and there is still room for improvement.

In terms of improving development efficiency, the one-component development method has two advantages.
Superior to component development methods. Among them, in particular, in Japanese Patent Application Laid-open No. 54-43037, 200
A thin layer of toner of less than .mu.m is formed and applied onto the sleeve.The toner is developed in the image area with a development efficiency close to 100%. Therefore, it has become possible to downsize and simplify the structure of the developing device and put it into practical use.

This was achieved because a thin layer of 200 μm or less could be formed on the developing roller. However, in any of the development methods, it is extremely difficult to form a thin layer of dry developer, and therefore, even in one-component development, the development device is configured to form a relatively thick layer. However, in view of the image quality, there is now a need to improve the clarity, resolution, etc. of developed images, and it is essential to develop a method for forming a thin layer of dry developer and an apparatus therefor.

However, the methods described above concerned the formation of a thin layer of magnetic toner. To make magnetic toner magnetic, a magnetic material must be added inside the toner. (magnetic materials are usually black)
There are problems such as poor color reproduction.

For this reason, methods for forming a thin layer of non-magnetic toner include using a cylindrical brush made of soft bristles like beaver hair and applying the toner to the brush, and developing rollers whose surface is made of fibers such as velvet. A method of applying with a doctor blade etc.) has been proposed.

However, when an elastic blade is used as a doctor blade for the above-mentioned fiber brush, it is possible to regulate the amount of toner, but uniform application is not achieved, and the fibers of the brush are simply rubbed by the fiber brush on the developing roller. Since no triboelectric charge is imparted to the toner existing between the toners, there is a problem in that fogging and the like are likely to occur.

Further, magnetic toner can easily prevent the toner from scattering by using magnetic force, but non-magnetic toner cannot utilize magnetic force and is likely to cause toner scattering inside the machine.

The above-mentioned disadvantages occur not only during copying but also when vibrations or shocks are applied during transport of the apparatus.

The present applicant has developed a developing device that is completely different from the conventional method described above, using non-magnetic toner and magnetic particles, and providing a magnetic particle restraining member opposite to a toner carrying member.
Regarding the working direction, a magnetic brush of magnetic particles is formed by the magnetic force of the magnetic field generating means upstream of the magnetic particle restraining member, the magnetic brush is restrained by the magnetic particle restraining member, and a thin layer of non-magnetic toner is deposited on the toner holding member. A method for forming such a material has already been proposed (Japanese Unexamined Patent Publication No. 143360/1983).

With this method, a non-magnetic toner developed image is obtained on the surface of the latent image carrier by setting the gap between the latent image carrier and the toner carrier in the developing section to be wider than the toner layer thickness and applying an alternating electric field. It has been put into practical use. As a result, developing efficiency is extremely high, and color developed images can now be obtained with a small and simple developing device configuration. In particular, during the two-component magnetic brush rubbing development, there were no rubbing marks generated in the solid image area, and a high quality solid image was obtained.

However, it has been desired to develop a developing method that further improves the developed image quality, for example, further improves gradation.

(Problems to be Solved by the Invention) The present invention has been made in view of the above-mentioned conventional circumstances, and has extremely high development efficiency and can be miniaturized to obtain developed images that are comparable to those of conventional development methods. The purpose is to provide a development method that is easy to use.

(Means for Solving the Problems) That is, the feature of the present invention is the development area of the developer carrier that faces the latent image carrier for holding the latent image, and the development area between the developer carrier and the latent image carrier. In an image forming method in which a latent image is developed with a non-magnetic toner while applying an alternating electric field between the toner and magnetic particles, the presence of magnetic particles in the development area of a developer carrier is caused by toner holding fine silica powder on the surface and magnetic particles. The amount is 5 to 80 m
g/cm2 preferably 10-70mg/c
A magnetic brush is formed so as to have an angle of 2 m2, and non-magnetic toner is reciprocated between the latent image holding member and the surface of the developer carrier and the surface of the magnetic brush formed on the surface of the developer carrier in the development area. An image forming method that develops a latent image.

The non-magnetic toner referred to here refers to an external magnetic field 5o.

00e refers to a toner that exhibits magnetization of 10 emu/g or less and that cannot be substantially excited as a magnetic toner.

The present inventors believe that the applicant of the present invention is
After proposing the publication, as a result of intensive research on its improvement,
Forming a clear developing magnetic pole in the developing section to perform locally concentrated development; - In the component-based development method, since frictional charging to the toner is mainly performed between the toner and the sleeve surface, the sleeve surface area is substantially reduced. to increase
The inventors have discovered that by using the above methods, it is possible to stabilize the triboelectric charging properties of the toner, stabilize the toner supply onto the sleeve, and improve image quality such as gradation and uniformity. Furthermore, the toner used in the present invention has extremely high efficiency in distributing the toner onto the toner carrier and onto the magnetic particles when applied to the present development method, and is therefore extremely advantageous in achieving the image forming method of the present invention. This is what I discovered. That is, in order to achieve the compact image forming method according to the present invention, the most important point is that the supplied toner is completely distributed onto the toner carrier and the magnetic particles;
The objective is to efficiently perform flying development using an alternating electric field from above both of them. For this purpose, it has been found that the best effect can be obtained by using a toner having fine silica powder supported on its surface.

The present developing method will be explained below along with examples.

FIG. 1 shows an embodiment of the present invention. In FIG. 1, the sleeve 22 rotates in the direction b, and the magnetic particles 27 circulate in the direction C accordingly. This causes contact and rubbing between the sleeve surface and the magnetic particle layer, and a non-magnetic toner layer is formed on the sleeve surface. Also, while the magnetic particles circulate in the C direction, some of them are attached to the non-magnetic blade 24 and the sleeve 22.
The amount of toner is regulated to a predetermined amount by the gap between the toner and the non-magnetic toner layer, and is applied onto the non-magnetic toner layer. That is, the non-magnetic toner is applied to both the sleeve surface and the magnetic particle surface, and the effect is substantially the same as that of increasing the sleeve surface area.

In the development area 32, one of the magnetic poles of the fixed magnet 23 is opposed to the latent image surface to form a clear development pole, and toner is developed by flying onto the sleeve and from the magnetic particles by an alternating electric field.

After development, the magnetic particles and undeveloped toner are collected into the developer container as the sleeve rotates. The sleeve 22 may be a paper tube or a cylinder made of synthetic resin, but if the surface of these cylinders is subjected to conductive treatment or made of a conductive material such as aluminum, brass, or stainless steel, it can be used as a developing electrode roller.

In the present invention, the amount of magnetic particles present on the sleeve surface in the development area 34 is a small amount of 5 to 80 mg/cm2, preferably 10 to 70 mg/cm2, in order to fully utilize the magnetic brush and the sleeve 22 surface. It must be.

If the amount of magnetic particles present on the sleeve surface is too large, the regulating force by the non-magnetic blade 24 will be weakened, and the sliding force between the sleeve and the magnetic particles will be reduced, making it impossible to smoothly charge the toner. Can not. Furthermore, during toner flying development, magnetic particles fly as well. There is a drawback that the latent image holder 3 is exposed to the latent image.

On the other hand, if the amount of magnetic particles present on the sleeve surface in the development area 34 is too small, the amount of toner applied to the development area decreases, resulting in density unevenness and poor image density.

The amount of magnetic particles on the sleeve surface is mainly found in the sleeve 22.
It can be adjusted by adjusting the gap between the fixed magnet 23, the position of the N1 pole of the fixed magnet 23, the magnetic flux density of the S1 pole, etc.

The method for measuring the amount of magnetic particles in the present invention will be described below. First, a magnetic brush made of only magnetic particles was formed on the sleeve, and the magnetic particles in a portion corresponding to the development area were sucked through a cylindrical paper through a filter, and the weight M (mg) of the brush was measured. Next, the magnetic particles remaining on the sleeve after the magnetic particles were attracted were sampled using a transparent adhesive tape, and the occupied area S (am2) of the attracted magnetic particles was determined.

The amount m (mg/cm") of magnetic particles present was calculated as follows.

m=M/S In addition, in the present invention, the toner amount ratio on the sleeve and on the magnetic particles is desirably within the following range in order to achieve the best development performance. If the ratio is larger than this, there will be too little toner on the magnetic particles and the effect of increasing the surface area on the sleeve will be small. If the ratio is smaller than this ratio, development will occur only from above the magnetic particles, resulting in poor image quality.

The method for measuring the amount of toner will be described below. First, a magnetic brush made of a mixture of magnetic particles and toner is formed on the sleeve, and then the magnetic brush is attracted by a fixed magnet, and the toner is washed away with a surfactant, so that the toner weight T2 (
mg) was measured.

Next, the toner that has fallen onto the sleeve from which the magnetic brush has been removed is transferred to the cylinder 3 in the same manner as in the method for measuring the amount of magnetic particles described above.
The toner weight on the sleeve T+ (m
g) was calculated.

The gap d between the tip of the non-magnetic blade 24 and the surface of the developing sleeve 22 at the point 25 is 50 to 700 μm.
1 preferably 100 to 600 μm. If the distance d is smaller than 50 μm, there is a drawback that magnetic particles, which will be described later, will clog and damage the sleeve. If it is larger than 700 μm, a large amount of non-magnetic toner and magnetic particles (described later) will leak out, making it impossible to form a thin layer.

In FIG. 1, 26 is a magnetic particle circulation area limiting member whose lower surface is in contact with the upper surface of the non-magnetic blade 24 and whose front end surface is an undercut surface.

Reference numerals 27 and 28 denote magnetic particles and non-magnetic toner which are sequentially accommodated in the toner supply container 21.

The bottom plate of the toner supply container 21 is extended below the developing sleeve 22, which is a toner holding member, to prevent toner from leaking to the outside. In order to further ensure the prevention of toner leakage to the outside, a leaked toner collecting container 29 is provided on the upper surface of the extended bottom plate to receive and restrain the leaked toner, and a leaked toner collection container 29 is provided on the top surface of the extended bottom plate. A scattering prevention member 30 is provided.

A voltage, which will be described later, is applied to this member 30.

The magnetic particles 27 generally have an average particle size of 30 to 100 μm, preferably 40 to 80 μm. Each magnetic particle may be made of only a magnetic material, a combination of a magnetic material and a non-magnetic material, or a mixture of two or more types of magnetic particles.

By first putting the magnetic particles 27 into the toner supply container 21, the magnetic particles 27 are applied to the sleeve surface area facing into the container 21, that is, the sleeve 22.
The magnets 23 in the sleeve 22 are located at various parts of the sleeve surface area from the magnetic member 31 for preventing leakage of magnetic particles or toner from the toner supply container 21 provided with the magnetic particles to the tip of the non-magnetic blade 24 serving as a magnetic particle restraining member. The magnetic particles are attracted and held by the magnetic field, and form a layer of magnetic particles that completely covers the sleeve surface area. When the non-magnetic toner 28 is put into the container 21 after the magnetic particles 27 are added, a large amount of the non-magnetic toner 28 is stored outside the magnetic particle layer as the first layer with respect to the sleeve 22 and exists as a second layer.

The first magnetic particles 27 preferably contain non-magnetic toner 28 in an amount of about 2 to 70% (by weight) of the magnetic particles, but may be composed of only magnetic particles. Furthermore, once the magnetic particles 27 are adsorbed and held in the sleeve surface area as a magnetic particle layer, they will not substantially shift to one side even if the device is vibrated or the device is tilted considerably, and the sleeve surface area will be held as a magnetic particle layer. It is maintained in a completely covered state.

Then, with the magnetic particles 27 and the non-magnetic toner 28 sequentially placed in the container 21 as described above, the magnet 2
A magnetic brush of magnetic particles is formed in the magnetic particle layer near the sleeve surface corresponding to the magnetic pole S1 position of No. 3 by the strong magnetic field of the magnetic pole.

In addition, the magnetic particle layer near the tip of the non-magnetic blade 24, which is a magnetic particle regulating member, is not affected by gravity, magnetic force, and the effects of the presence of the non-magnetic blade 24 even when the sleeve 22' is rotated in the direction of the arrow. The regulating force based on the sleeve 22
Due to the balance with the feeding force in the direction of movement, it accumulates at point 25 on the surface of the sleeve 22, to some extent! II can be formed, but wJ can form a stationary layer.

When the sleeve 22 is rotated in the direction indicated by the arrow, by appropriately selecting the arrangement position of the magnetic pole, the fluidity of the magnetic particles 27, and the magnetic properties, the magnetic brush circulates in the direction of the arrow C near the magnetic pole S2, forming a circulating layer. form. As the sleeve 22 rotates, the magnetic particles in the circulation layer that are relatively close to the sleeve 22 rise from the vicinity of the magnetic pole S2 onto the stationary layer that is downstream of the rotation of the sleeve. In other words, it receives a force that pushes it upward. The pushed up magnetic particles are
Since the upper limit of the circulation area of the magnetic particles is determined by the magnetic particle circulation area limiting member 26 provided on the upper part of the non-magnetic blade 24, the magnetic particles do not climb onto the non-magnetic blade 24, but descend due to gravity, and return to the vicinity of the magnetic pole S2. Return to In this case, the magnetic particles that receive a small push-up force due to being located far from the sleeve surface are removed by the magnetic particle circulation area limiting member 26.
In some cases, the object may fall before reaching the point. In other words, in the circulation layer, the magnetic brush of the magnetic particles is circulated as shown by arrow C due to the magnetic force and frictional force caused by gravity and magnetic poles, and the fluidity (viscosity) of the magnetic particles. The non-magnetic toner 28 is successively taken in from the toner layer above the toner layer and returned to the lower part of the developer supply container 21, and this cycle is repeated as the sleeve 22 rotates.

As the developing bias voltage 34, an alternating voltage having the same peak voltage on the plus side and the minus side, or a DC voltage superimposed on this alternating voltage can be used.

For example, dark area latent image potential +800V, bright area latent image potential +200V
For example, by superimposing a DC voltage of +300 V on the sleeve 22, the waveform peak voltage vpp3 is applied to the electrostatic latent image of V.
oo~2000V.

An alternating voltage selected in the frequency range of 200 to 3000 Hz is applied to maintain the photosensitive drum 3 at ground potential.

Generally, the electrical resistance of magnetic brushes is relatively high (108Ω
cm) Therefore, it is better to have a high VPP during the peak voltage of the developing bias (for example, 800 cm or more) and a frequency of 60 cm.
0Hz or more, preferably 800Hz or more, more preferably IKHz or more (preferably 10oO to 3000Hz
), the higher the value, the better the image quality with sufficient density was obtained. In any case, the upper limit of VPP is determined by the gap discharge limit value of the developing section, and the lower limit is determined by the toner flight limit value on the sleeve, top, and magnetic particles.

Taking the above into consideration, the resistance of the entire developing magnetic brush is 1015 Ωcm to 1 in the thickness direction of the developing brush when the developing brush is in contact with the latent image holder 1.
A level of 0'Ωcm is good.

Incidentally, the resistance value of the magnetic particles and magnetic brush mentioned in the present invention means that a magnetic brush of about 50 mg/cm 2 of magnetic particles is formed on the developing sleeve 22 by the developing device shown in FIG. Opposite this, there is a gap of about 3 between the developing sleeve and
It was calculated from the current value that flows when a DC voltage of 200 V is applied to a circuit in which a conductive metal drum with a constant resistance of 00 μm is provided and a resistor of about IMΩ is connected in series with the drum.

In the developing method according to the present invention, phenomena in the developing section 32 will be described below.

FIGS. 2 and 3 are enlarged explanatory views of the developing section of the developing method according to the present invention. 50 is the latent image charge in the dark area on the latent image carrier. 28 is a non-magnetic toner. 34 is an alternating voltage power source on which a DC component is superimposed. Figure 2 shows sleeve 2
When the positive waveform component of the alternating voltage is added to 2, the 3rd
The figure shows the case where a negative waveform component of the alternating voltage is added. The polarity of the latent image charge is shown as negative, and the polarity of the developer is shown as positive.

The resistance of the developing brush 51 is relatively large (approximately 108 Ωcm)
Therefore, depending on the charging/discharging time constant of the charge due to the material of the developing brush 51 itself and other factors, the developing brush 51 has a frictional charge or a mirror charge with the toner 28, and a latent charge on the latent image carrier 3. Image electric field and latent image carrier 3 top and sleeve 22
There will be charge injected by the alternating electric field between.

When the electric field due to the latent image charge 50 in the dark area on the latent image holder 3 matches the electric field due to the alternating electric field, the developing brush 51 is in the maximum bending state in the direction of the sleeve 22 .

When the electric field due to the latent image charge on the latent image carrier 3 and the electric field due to the alternating electric field do not match in direction, the bending of the developing brush 51 becomes small.

In any case, as mentioned above, the developing brush 5 is
1 is in a state of minute but intense vibration, and the fog toner that has adhered excessively on the latent image holder is rubbed by the developing brush, removed from the latent image holder 3, and drawn back onto the brush. Further, due to the vibration of the brush, the toner is easily separated from the brush 51 and is easily supplied to the latent image holding member 3', so that the image density is also improved.

Further, the vibration of the brush 51 loosens the toner within the brush 51, which contributes to improving image density and preventing ghosts. Furthermore, if this vibration state is severe, a portion of the magnetic brush comes off from the brush or the sleeve, causing reciprocating motion between the latent image holder and the sleeve surface. The kinetic energy of this reciprocating brush is large and efficient, and the above-mentioned vibration effect is expected. The behavior of the magnetic particles in the developing section described above can be seen using a high-speed camera at 8.00% per second.
This phenomenon was observed as a result of high-speed photography of 00 frames.

As the silica fine powder used in the present invention, any silica fine powder manufactured by a conventionally known wet method or dry method can be used.

Various conventionally known methods can be used to produce the silica fine powder used in the present invention by a wet method. For example, the decomposition of sodium silicate with an acid, shown in the general reaction formula (the reaction formula is omitted below), is Na2ClXSiO2+HC
j2+Hz o-5tt)z ・nH20+Na (4) Other methods include decomposition of sodium silicate with ammonia salts or alkali salts, and a method of generating alkaline earth metal silicate from sodium silicate and then decomposing it with acid to produce silicic acid. There are methods such as converting a sodium silicate solution into silicic acid using an ion exchange resin, and using natural silicic acid or silicate.

As the silicic acid fine powder referred to herein, any of anhydrous silicon dioxide (silica) and other silicates such as aluminum silicate, sodium silicate, potassium silicate, magnesium silicate, and zinc silicate can be used.

Commercially available fine silica powder synthesized by a wet method used in the present invention includes, for example, those commercially available under the following trade names.

Carplex Shionogi & Co. Nip Seal Japan Silica Tora Seal. Fine Seal Tokuyama Express Delivery Vita Seal
Multi-wooden fertilizer JILTON, Silnetx Mizusawa Kagaku Starsil
Shinshin Kagaku Himezil Ai tS Yakuhin Thyroid Fuji Davison Kagaku Hi-sil (
High Seal) Pittsburgh Plate
Glass COl (Bippagu Plate Glass) Durosi! (Douro Seal) Fillstoff
-Ultrasil Ge5el 1sc
haf (Ultra Seal) t M
arquart Manosi 1 Hardman
andHolden (Hardman and Holden) HOesch (Herash) Che mi
s ch e Fabrik, Hoes
c h K-G (Hiemitsusche Fabrik Herrash) Sil-3tone 5toner Rub
b (Sil-Stone) er Co,
(Stoner Lover) Nalco Na1co C
hemCo, (Narco Chemirikiru) Quso (shoes) Ph1ladel
phia Quartz C 05 (Philadelphia Quartz) Santocell Mon5anto 1a
h (santocell) emical
Co.

(Monsando Chemical) Imsil l1linois
Minerals Co.

(Illinois Mineral) Calcium 5ilikat (Calcium Silicat) Chemische Fabri (Hetsch) Calsil (Fiillstof)
f -Gesel 1schaft Marquart Fortafil Imperia
l Chemical Indu stries, Ltd.

(Imperial Chemical Industries) Microcal J o se p
h Cro 5field & 5ons, Ltd. (Jinicef Crosfield & Sons) Manosil Hardman a
ndHolden Vulkasil Farbenfabik en Bryer, A.

-G, (Falpenfabriken Purchaser) Tuflnit Durham Ch
emicals, Ltd.

(Doulham Chemicals) Silmos Shiraishi Kogyo Starex Shinshin Kagaku Fricosil Tagi Himata The dry method silica fine powder used in the present invention is produced by a conventionally known technique.

For example, this method utilizes a thermal decomposition oxidation reaction of silicon tetrachloride gas in an oxyhydrogen flame, and the basic reaction formula is as follows.

S i ca14+2H2+o2-*S i o2 +
4HC1 Also in this manufacturing process, other metal halide compounds such as aluminum chloride or titanium chloride,
It is also possible to obtain composite fine powders of silica and other metal oxides by using them together with silicon halogen compounds, and the present invention also includes these.

Examples of commercially available silica fine powders include those available under the following trade names.

AERO3IL 130 (
Japan Aerosil Co., Ltd.) 200T60
0 0X80 0X170 0K84 Cab-0-SiJZ M-5
(CABOT) MS-7MS
-5 H-5 WaclerHDK
N20N20(WACKER-CHE
■15GMBH)
N20ED-C
Fine 5ilica (Dow Corning Company) Fransol (Fransi1 Company) The particle size is 0.001 to 2 μm as the average primary particle size.
It is desirable that it be within the range of 0.00, particularly preferably 0.00
It is preferable to use fine silica powder within the range of 2 to 0.2 μm.

It is more desirable that the surface of the silica fine powder of the present invention be treated with a surface treatment agent such as an organosilicon compound or an organotitanium compound in order to make it hydrophobic.

As for the degree of hydrophobization, it is desirable that the degree of hydrophobization is 30 or more as measured by a methanol titration test.

Examples of organosilicon compounds are hexamethyldisilazane, trimethylsilane, trimethylchlorosilane, trimethylethoxysilane, dimethyldichlorosilane, methyltrichlorosilane, allyldimethylchlorosilane, allyl phenyldichlorosilane, benzyldimethylchlorosilane, bromomethyl Dimethylchlorosilane, α-chloroethyltrichlorosilane, p-chloroethyltrichlorosilane, chloromethyldimethylchlorosilane, chloromethyldimethylchlorosilane, triorganosilyl mercaptans, e.g. trimethylsilylmercaptan, triorganosilylacrylates, e.g. vinyldimethyla, setoxysilane , further dimethylethoxysilane, dimethyldimethoxysilane, hexamethyldicycloxane, 1,3
- divinyltetramethyldisiloxane, 1,3-diphenyltetramethyldisiloxane, having from 2 to 12 siloxane units per molecule and containing one Si-bonded hydroxyl group in each terminally located unit; There is dimethylpolysiloxane. These may be used as one fffi or as a mixture of two or more.

The organic titanium compound used in the present invention is a titanate coupling agent that reacts with or adsorbs the hydroxyl group on the surface of the fine silica powder or adsorbed water to form a film on the surface of the fine silica powder, and includes, for example, The surface treatment agent may be used alone or in a mixed system of two or more.

In the method of treating fine silica powder with a silane coupling agent or a titanate coupling agent, the surface treatment agent used in the present invention can be used to treat chemically or physically bound water present on the surface of fine silica powder. Since it is easily coated through a chemical reaction, both dry and wet methods can be employed, and a wide range of treatment methods can be used. For example, fine silica powder and an appropriate amount of surface treatment agent are put into a mixer such as a Henschel mixer or a ball mill, and then dry mixed, or a titanium-based coupling agent is dissolved in an appropriate solvent and then fine silica powder is added. Various methods can be used, such as a method in which the solvent is added, mixed, and the solvent is removed, or a method in which a spray heat treatment is performed using a spray dryer.

The amount of these surface treatment agents used to treat the silica fine powder is 0.01 to 20% by weight (preferably o, i to 10% by weight).

In combination with these surface treatment agents, the general formula % (R is an alkoxy group or a chlorine atom, m is an integer of 1 to 3, Y is an amino group, a vinyl group, a glycidoxy group, a mercapto group, a methacrylic group, a ureido group) hydrocarbon group containing at least one or two or more types, n is an integer of 3 to 1)
It is also possible to treat with a silane coupling agent shown in

The preferred weight of the hydrophobizing agent such as a silane coupling agent compound to be treated with respect to the silica fine powder is preferably as follows:
It is desirable that the amount is 0.1 to 30 wt %, more preferably 0.5 to 2 wt %, based on the silica fine powder.

The degree of hydrophobization of the final treated silica fine powder was 30 as the hydrophobization level measured by methanol titration test.
A developer preferable for use in the developing method of the present invention can be obtained when it is hydrophobized to exhibit a value within the above range.

Here, the methanol titration test is an experimental test to confirm the degree of hydrophobization of fine silica powder having a hydrophobized surface. The "methanol titration test" specified herein for evaluating the degree of hydrophobicity of the treated silica fine powder is carried out as follows: 0.2 g of the sample silica fine powder is placed in an Erlenmeyer flask with a capacity of 250 mJ:L. methanol is added to 50 mλ of water. Titrate methanol until the entire amount of silica is wetted from the buret. At this time, the solution in the flask is constantly stirred with a magnetic stirrer. The end point is when the entire amount of silica fine powder is wetted in the liquid. The degree of hydrophobization is expressed as the percentage of methanol in the liquid mixture of methanol and water at the end point.

In addition, the applied amount of these treated silica fine powders is effective when the amount is 0.01 to 20% based on the weight of the toner, and particularly preferably when it is added 0.1 to 3%, excellent stability is achieved. It exhibits positive chargeability. The preferred form of addition is 0.01 to 0.01 to the weight of the toner.
3! % of the treated silica fine powder is preferably attached to the surface of the toner particles.

On the other hand, as the binder resin of the toner used in the present invention,
*Polymer of styrene and its substituted products such as polystyrene, poly p-chlorostyrene, polyvinyltoluene: styrene-p-chloro, styrene copolymer, styrene-propylene copolymer, styrene-vinyltoluene copolymer,
Styrene-vinylnaphthalene copolymer, styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-butyl acrylate copolymer, styrene-octyl acrylate copolymer, styrene-methyl methacrylate copolymer Polymer, styrene-ethyl methacrylate copolymer, styrene-butyl methacrylate copolymer, styrene-acrylic-aminoacrylic copolymer, styrene-aminoacrylic copolymer, styrene-alpha chloromethyl methacrylate copolymer combination, styrene-acrylonitrile copolymer, styrene-vinyl methyl ether copolymer,
Styrene-vinylethyl ether copolymer, styrene-
Styrenic compounds such as vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-acrylonitrile-indene copolymer, styrene-maleic acid copolymer, and styrene-maleic acid ester copolymer Copolymers: polymethyl methacrylate, polybutyl methacrylate, polyvinyl chloride, polyvinyl acetate, polyethylene, polypropylene, polyester, polyurethane, polyamide, epoxy resin, polyvinyl butyral, polyacrylic acid resin, rosin-modified rosin, terpene resin, phenolic resin , aliphatic or alicyclic hydrocarbon resin, aromatic petroleum resin, chlorinated paraffin, paraffin wax, etc. can be used alone or in combination.

Any suitable pigment or dye can be used as a color viewing agent in the toner. For example, carbon black, iron black,
There are known facial cleansers such as phthalocyanine blue, ultramarine blue, quinacridone, and benzidine yellow.

Also, as charge control agents, amino compounds, quaternary ammonium compounds, organic dyes, especially basic dyes and their salts, benzyldimethyl-hexadecyl ammonium chloride, decyl-trimethylammonium chloride, nigrosine base, nigrosine hydrochloride, safranin γ
Also, crystal violet, metal-containing dyes, salicylic acid metal-containing compounds, etc. may be added. Furthermore, magnetic powder may be added to an extent that does not impede the effects of the present invention.

The toner structure described above may be used for a toner produced by a commonly used mixing-pulverization method, or may be used for the wall material or core material, or both, of a microcapsule toner.

Composition of Materials The magnetic particles for toner application used in the present invention include, for example, surface oxidized or unoxidized iron, nickel, cobalt,
Metals such as manganese, chromium, rare earths, and alloys or oxides thereof can be used. Moreover, there are no special restrictions on the manufacturing method.

It is also possible to coat the surface of the magnetic particles with a resin or the like. As a method for this, any conventionally known method can be applied, such as a method in which a coating material such as a resin is dissolved in a solvent or coated with a thin layer and adhered to the carrier, or a method in which a powder is mixed in a vehicle.

Substances that adhere to the carrier surface vary depending on the toner material, but include polytetrafluoroethylene, monochlorotrifluoroethylene polymer, polyvinylidene fluoride, silicone resin, polyester resin, ditertiary resin, etc.
It is appropriate to use metal complexes of butylsalicylic acid, styrene resins, acrylic resins, polyamides, polyvinyl butyral, nigrosine, aminoacrylate resins, basic dyes and their lakes, fine silica powder, fine alumina powder, etc., singly or in combination. However, it is not necessarily limited to this.

The amount of the above compound to be treated may be appropriately determined so that the carrier satisfies the above conditions, but generally the total amount is 0.1 to 30% by weight, preferably 0.5 to 30% by weight, based on the carrier of the present invention.
20% by weight is desirable.

〔Example〕

The present invention will be explained in more detail with reference to Examples below. The parts given in the examples are parts by weight.

The developing device shown in FIG. 1 was used.

In the embodiment apparatus, the photosensitive drum 3 rotates in the direction of arrow a at a circumferential speed of 6 mm/sec. 22 is 66 in the direction of the arrow
Outer diameter 32mm, thickness 0.8 that rotates at a circumferential speed of mm/sec.
The sleeve is made of stainless steel (SUS304), and its surface is coated with amorphous sunburst using #600 alundum abrasive grains, and the roughness of the circumferential surface is reduced to 0.8 μm (R).
,=).

On the other hand, a sintered ferrite type magnet 23 was fixedly disposed inside the rotating sleeve 22, and the magnetic pole arrangement was as shown in FIG. 1, and the maximum value of the surface magnetic flux density was about 800 Gauss.

The non-magnetic blade 24 is made of non-magnetic stainless steel with a thickness of 1.2 mm, and the amount of magnetic particles on the sleeve is 30 to 60.
The blade-sleeve gap was set to 300 parts m so that mg/crd.

On the surface of the photosensitive drum 3 facing this sleeve 22,
As an electrostatic latent image, a charge pattern of +600 V in the dark area and +150 V in the bright area was formed, and the distance from the sleeve surface was set to 300 μm. Then, a voltage with a frequency of 800 Hz, a peak-to-peak value of 1.4 KV, and a center value of +300 cm was applied to the sleeve by the power source 34 to perform development.

Example 1 The surface of dry silica (-particle size 20 μm) obtained by thermally decomposing silicon tetrachloride gas in an oxyhydrogen flame on 100 parts of red particles with an average particle size of 10 μm consisting of the following was treated with chlorotrimethylsilane. Hydrophobization treatment and methanol titration Hydrophobization degree 60
0.6 part of treated silica was added to prepare a toner.

8 parts of this toner and 100 parts of ferrite powder (particle size 2oo-300 mesh) whose surface has been treated with polymethyl methacrylate.
When the mixture was mixed with the following parts and applied to the developing device, an extremely good image with no fog was obtained. At that time, the ratio of the amount of toner on the sleeve to the amount of toner on the magnetic particles (TI/T2
) was 115, and the distribution of toner to both was smooth. This ratio hardly changed even in special environments of high temperature, high temperature, low temperature and low humidity.

Example 2 The same procedure as in Example 1 was carried out except that the surface treatment of the silica was carried out with isopropyl triisostearoyl titanate. The degree of hydrophobicity of the obtained treated silica was 40, and the toner on the sleeve and magnetic particles was The distribution was smooth with TI/T2=1/2, and good images were obtained.

Example 3 The same procedure as in Example 1 was performed except that R-972 silica from Nippon Aerosil Co., Ltd. was used. As a result, T r / T 2
= 1/7, the toner was distributed smoothly and a good image was obtained.

Example 4 Treated silica (hydrophobicity degree 80) obtained by treating the surface of wet-process silica (-particle size 30 μm) obtained by decomposing sodium silicate with acid with polydimethylsiloxane (oil) was used. The same procedure as in Example 1 was carried out except that
T1/T2=1/4, the toner distribution was smooth and a good image was obtained.

Comparative Example 1 The same procedure as in Example 1 was carried out except that silica was not added. As a result, T+ /T2 = 2.571, and toner distribution was not successful.

(Effects of the Invention) As explained above, according to the present invention, in a developing device using magnetic particles with a simple configuration, by interposing a small amount of magnetic particles in the development area, there is no ground blurring and good gradation is achieved. Good image quality without negative characteristics could be obtained in various environments.

Furthermore, by efficiently distributing the toner contributing to development on the sleeve and on the magnetic particles, and performing flying development from both, it was possible to achieve a development efficiency of nearly 100% in an alternating electric field.

This makes it possible to downsize and simplify the configuration of the developing device.

Also, at least by means of an alternating electric field, the brush of magnetic particles according to the present invention was brought into contact with the latent image carrier and vibrated, thereby being able to remove the soil brightener adhering to the latent image carrier.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional front view of a developing device using a developing method according to the present invention. FIGS. 2 and 3 are enlarged explanatory views of the developing section according to the developing method according to the present invention. In the figure, 3 is a latent image holding member, 21
2 is a developer supply container, 22 is a non-magnetic sleeve, 23 is a fixed magnet, 24 is a non-magnetic blade, 26 is a magnetic particle circulation area limiting member, 27 is a magnetic particle, 28 is a non-magnetic toner, and 29 is a developer supply container section. , 30 is a scattering prevention member, 31 is a magnetic member, 32 is a developing area, 34 is a bias power source, 50 is an electrostatic latent image, and 51 is a magnetic brush.

Claims (1)

[Claims] The latent image is developed with non-magnetic toner while applying an alternating electric field between the developer carrier and the latent image carrier in the development area of the developer carrier facing the latent image carrier for holding the latent image. In the image forming method, a magnetic brush is used to form a toner having fine silica powder on its surface and magnetic particles so that the amount of magnetic particles present is 5 to 80 mg/cm^2 in the development area of a developer carrier. and developing the latent image while reciprocating the non-magnetic toner between the latent image holding member and the surface of the developer carrying member and the surface of the magnetic brush formed on the surface of the developer carrying member in the development area. image forming method.